Does anyone know or can you help in determining what would work as a non flammable , antifreeze solution to be used in fire prevention systems located in below freezing temperatures.?

additionally, could you prepare a saline solution to a point where the freezing point would be substantially lowered, , using approx 30 grams or .5/mole salt per KG or roughly 120 grams per gallon... to lower by approx 1.85 deg...each multiple? is there a limit to this freezing point depression,? would you pipes carrying this solution in cold temperatures be free from freezing/bursting concerns ?